The Ototara Limestone, commonly known as Oamaru stone, is a bright cream- colored limestone from the area around Oamaru, New Zealand. The time of origin of the stone will be chronologically ordered in the regional geological stage of Whaingaroan. This stage corresponds to the global Oligocene and is therefore in absolute age values before the period of 33.9 to 28.1 million years associate.
The area in which the Ototara Limestone is found, belongs to a larger cohesive landscape that covers the southern part of Canterbury and spacious coastal area of Otago. The Oamaru stone is mined at present only in Parkside Quarry ( Quarry ) at Weston, 6 km north-west from the center of Oamaru located. In the area around Oamaru a prevalence of about 450 megatons of the quality of Ototara Limestone is suspected.
The limestone is coarse textured, porous, and strength despite its relatively light weight. Its color is light brown and creamy- white temporarily. His partial large, colored stripes give sculptures that are made from stone, a special atmosphere. The stone is easy to cut and therefore is also particularly in cuboid shape as a building material.
The content of calcium carbonate CaCO3 is between 86 % and 98%, but usually about 93%. The proportions of silica, SiO2 will be around 1%, iron ( III ) oxide Fe2O3 0.43 % and aluminum oxide Al2O3 at 0.5%. The Ototara Limestone has to be the reputation of the best quality limestone in the Otago region because of its nature and its properties.
Since the limestone has good machining properties and is very appealing due to its color structure, it is very often used in house construction and facade design. Especially in Otago, but also nationwide, the Oamaru Stone found in the construction of stone buildings since the 1860s use. Initially, the limestone was used mostly in churches, buildings of banks, town halls, theater buildings, and other public buildings or private residences as a supporting stone and at the same time as an artistic medium.
The image of the historic town of Oamaru is characterized by buildings of Oamaru Stone. Many of these buildings were designed by the architectural community Forrester & Lemon. In other structures of light stone with a hard, blue-gray basalt ( " Bluestone ") was used as a contrast, as the Dunedin Railway Station, the University of Otago Registry Building and the Christchurch Arts Centre.
Today, the Oamaru stone is used as building material only for facade cladding, for jewelry -like interior walls or smaller buildings, as the limestone, because of its low strength earthquake resist bad. 2009 tried the Otago District Council to ban the limestone as a building material to build houses. For the production of stone sculptures of limestone is widely used, some local artists work almost exclusively with this stone.